Special Issue “Synthesis, Characterization and Performance Enhancement of Electrode and Biomaterial Coatings”

Functional materials are extensively employed across diverse domains, including energy storage systems [1,2], electronic devices [3], and medical implants [4], where their performance significantly influences the efficiency, reliability, and longevity of related technologies [5,6]. However, in real-world applications, these materials often encounter substantial challenges [7], such as inadequate electrical conductivity, limited mechanical strength, severe interfacial side reactions in electrode materials, and poor biocompatibility and corrosion resistance in biomaterials. To address these issues, surface coating modification has emerged as a highly effective strategy to enhance their physical, chemical, and mechanical properties [8], thereby meeting the multifaceted demands of modern applications.

Surface coating technologies for functional materials have garnered significant attention within the materials science and engineering community [9], particularly in improving the performance of critical components such as electrodes and biomaterials. For example, electrode materials in energy storage systems—such as lithium-ion batteries (LIBs) and electrochemical capacitors—are prone to mechanical degradation and undesirable side reactions due to repetitive charge/discharge cycles, which can lead to substantial performance deterioration over time [10]. Coating these electrodes with materials exhibiting superior electrical conductivity and chemical stability, including metal oxides, ceramics, graphene, and conductive polymers, can markedly enhance their structural integrity [11]. This, in turn, optimizes the interfacial reaction kinetics between the electrode and electrolyte [12], resulting in improved cycle stability and enhanced capacity retention [13]. Moreover, surface coatings can significantly lower the intrinsic resistance of electrode materials and boost ion transport rates [14], both pivotal factors for enhancing the power density and operational efficiency of energy storage devices.

Coating technologies also demonstrate remarkable potential in advancing biomaterials [15]. For medical implants, biocompatibility, corrosion resistance, and controlled degradability are paramount for ensuring seamless integration with human tissues and long-term safety. Metals, commonly used in orthopedic and dental implants [16], often exhibit limited corrosion resistance and biocompatibility, potentially triggering adverse biological reactions. By applying bioactive coatings such as bioceramics or biofunctional polymers to metal surfaces, these limitations can be mitigated, leading to improved tissue integration and promoting the regeneration of bone or other tissues. For instance, bioceramic coatings such as hydroxyapatite [17], which closely resemble the inorganic composition of bone, facilitate faster osseointegration, while conductive polymer coatings can enhance the electrical properties of implants, proving especially advantageous in applications such as neural tissue engineering.

Notably, surface coatings not only augment the intrinsic properties of functional materials but also allow for precise optimization of targeted functionalities by carefully controlling parameters such as coating thickness, microstructure, and composition. For example, ceramic coatings are widely adopted in high-temperature electrode materials due to their excellent thermal stability and corrosion resistance, whereas metal oxide coatings are frequently employed in electrochemical storage devices for their robust chemical inertness. Additionally, graphene and two-dimensional materials [18,19], known for their exceptional conductivity and mechanical flexibility as coatings, are optimal for improving the electrochemical performance of LIBs and supercapacitors. By judiciously selecting and designing coating materials, it is possible to enhance conductivity, reinforce mechanical durability, minimize detrimental side reactions, and elevate the overall performance of energy storage systems.

This Special Issue seeks to provide an in-depth exploration of the design, fabrication, and application of surface coatings for functional materials. Emphasis will be placed on the comparative evaluation and optimization of various coating technologies to elucidate the underlying mechanisms by which surface modification strategies improve material performance. The scope includes the investigation of ceramics, metals, metal oxides, graphene, and conductive polymers, both as individual materials and as surface coatings, with a focus on their roles in enhancing mechanical robustness and electronic and ionic conductivity and mitigating interfacial degradation. Furthermore, the Issue will address emerging trends and future directions in coating technology, offering novel insights and guidelines for the development of next-generation coatings for functional materials across a wide range of applications.